Shell: Make Immediate expression invocation fallible

This removes a whole bunch of FIXMEs in the immediate expr
implementations as well :^)

3 files changed, 79 insertions, 79 deletions

diff --git a/Userland/Shell/AST.cpp b/Userland/Shell/AST.cpp
index a964b34a7b..ffd263fe2d 100644
--- a/Userland/Shell/AST.cpp
+++ b/Userland/Shell/AST.cpp
@@ -2048,7 +2048,7 @@ ErrorOr<void> ImmediateExpression::dump(int level) const
 
 RefPtr<Value> ImmediateExpression::run(RefPtr<Shell> shell)
 {
-    auto node = shell->run_immediate_function(m_function.name, *this, arguments());
+    auto node = shell->run_immediate_function(m_function.name, *this, arguments()).release_value_but_fixme_should_propagate_errors();
     if (node)
         return node->run(shell);
 
diff --git a/Userland/Shell/ImmediateFunctions.cpp b/Userland/Shell/ImmediateFunctions.cpp
index 7a0d1e2f31..4925c8dbb0 100644
--- a/Userland/Shell/ImmediateFunctions.cpp
+++ b/Userland/Shell/ImmediateFunctions.cpp
@@ -10,7 +10,7 @@
 
 namespace Shell {
 
-RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments, bool across)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_impl(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments, bool across)
 {
     auto name = across ? "length_across" : "length";
     if (arguments.size() < 1 || arguments.size() > 2) {
@@ -59,18 +59,18 @@ RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invokin
         if (expr_node->is_list())
             mode = List;
         else if (expr_node->is_simple_variable()) // "Look inside" variables
-            mode = const_cast<AST::Node*>(expr_node)->run(this)->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors()->is_list_without_resolution() ? List : String;
+            mode = TRY(const_cast<AST::Node*>(expr_node)->run(this)->resolve_without_cast(this))->is_list_without_resolution() ? List : String;
         else if (is<AST::ImmediateExpression>(expr_node))
             mode = List;
         else
             mode = String;
     }
 
-    auto value_with_number = [&](auto number) -> NonnullRefPtr<AST::Node> {
-        return AST::make_ref_counted<AST::BarewordLiteral>(invoking_node.position(), String::number(number).release_value_but_fixme_should_propagate_errors());
+    auto value_with_number = [&](auto number) -> ErrorOr<NonnullRefPtr<AST::Node>> {
+        return AST::make_ref_counted<AST::BarewordLiteral>(invoking_node.position(), TRY(String::number(number)));
     };
 
-    auto do_across = [&](StringView mode_name, auto& values) {
+    auto do_across = [&](StringView mode_name, auto& values) -> ErrorOr<RefPtr<AST::Node>> {
         if (is_inferred)
             mode_name = "infer"sv;
         // Translate to a list of applications of `length <mode_name>`
@@ -80,9 +80,9 @@ RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invokin
             // ImmediateExpression(length <mode_name> <entry>)
             resulting_nodes.unchecked_append(AST::make_ref_counted<AST::ImmediateExpression>(
                 expr_node->position(),
-                AST::NameWithPosition { String::from_utf8("length"sv).release_value_but_fixme_should_propagate_errors(), invoking_node.function_position() },
+                AST::NameWithPosition { TRY(String::from_utf8("length"sv)), invoking_node.function_position() },
                 NonnullRefPtrVector<AST::Node> { Vector<NonnullRefPtr<AST::Node>> {
-                    static_cast<NonnullRefPtr<AST::Node>>(AST::make_ref_counted<AST::BarewordLiteral>(expr_node->position(), String::from_utf8(mode_name).release_value_but_fixme_should_propagate_errors())),
+                    static_cast<NonnullRefPtr<AST::Node>>(AST::make_ref_counted<AST::BarewordLiteral>(expr_node->position(), TRY(String::from_utf8(mode_name)))),
                     AST::make_ref_counted<AST::SyntheticNode>(expr_node->position(), NonnullRefPtr<AST::Value>(entry)),
                 } },
                 expr_node->position()));
@@ -100,7 +100,7 @@ RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invokin
         if (!value)
             return value_with_number(0);
 
-        value = value->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors();
+        value = TRY(value->resolve_without_cast(this));
 
         if (auto list = dynamic_cast<AST::ListValue*>(value.ptr())) {
             if (across)
@@ -109,7 +109,7 @@ RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invokin
             return value_with_number(list->values().size());
         }
 
-        auto list = value->resolve_as_list(this).release_value_but_fixme_should_propagate_errors();
+        auto list = TRY(value->resolve_as_list(this));
         if (!across)
             return value_with_number(list.size());
 
@@ -145,7 +145,7 @@ RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invokin
         if (!value)
             return value_with_number(0);
 
-        value = value->resolve_without_cast(*this).release_value_but_fixme_should_propagate_errors();
+        value = TRY(value->resolve_without_cast(*this));
 
         if (auto list = dynamic_cast<AST::ListValue*>(value.ptr())) {
             if (!across)
@@ -165,7 +165,7 @@ RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invokin
         }
 
         // Evaluate the nodes and substitute with the lengths.
-        auto list = value->resolve_as_list(this).release_value_but_fixme_should_propagate_errors();
+        auto list = TRY(value->resolve_as_list(this));
 
         if (!expr_node->is_list()) {
             if (list.size() == 1) {
@@ -189,17 +189,17 @@ RefPtr<AST::Node> Shell::immediate_length_impl(AST::ImmediateExpression& invokin
     }
 }
 
-RefPtr<AST::Node> Shell::immediate_length(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_length(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     return immediate_length_impl(invoking_node, arguments, false);
 }
 
-RefPtr<AST::Node> Shell::immediate_length_across(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_across(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     return immediate_length_impl(invoking_node, arguments, true);
 }
 
-RefPtr<AST::Node> Shell::immediate_regex_replace(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_regex_replace(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 3) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 3 arguments to regex_replace", invoking_node.position());
@@ -208,7 +208,7 @@ RefPtr<AST::Node> Shell::immediate_regex_replace(AST::ImmediateExpression& invok
 
     auto pattern = const_cast<AST::Node&>(arguments[0]).run(this);
     auto replacement = const_cast<AST::Node&>(arguments[1]).run(this);
-    auto value = const_cast<AST::Node&>(arguments[2]).run(this)->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments[2]).run(this)->resolve_without_cast(this));
 
     if (!pattern->is_string()) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected the regex_replace pattern to be a string", arguments[0].position());
@@ -225,16 +225,16 @@ RefPtr<AST::Node> Shell::immediate_regex_replace(AST::ImmediateExpression& invok
         return nullptr;
     }
 
-    Regex<PosixExtendedParser> re { pattern->resolve_as_list(this).release_value_but_fixme_should_propagate_errors().first().to_deprecated_string() };
+    Regex<PosixExtendedParser> re { TRY(pattern->resolve_as_list(this)).first().to_deprecated_string() };
     auto result = re.replace(
-        value->resolve_as_list(this).release_value_but_fixme_should_propagate_errors()[0],
-        replacement->resolve_as_list(this).release_value_but_fixme_should_propagate_errors()[0],
+        TRY(value->resolve_as_list(this))[0],
+        TRY(replacement->resolve_as_list(this))[0],
         PosixFlags::Global | PosixFlags::Multiline | PosixFlags::Unicode);
 
-    return AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), String::from_utf8(result).release_value_but_fixme_should_propagate_errors(), AST::StringLiteral::EnclosureType::None);
+    return AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), TRY(String::from_utf8(result)), AST::StringLiteral::EnclosureType::None);
 }
 
-RefPtr<AST::Node> Shell::immediate_remove_suffix(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_remove_suffix(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to remove_suffix", invoking_node.position());
@@ -242,23 +242,23 @@ RefPtr<AST::Node> Shell::immediate_remove_suffix(AST::ImmediateExpression& invok
     }
 
     auto suffix = const_cast<AST::Node&>(arguments[0]).run(this);
-    auto value = const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this));
 
     if (!suffix->is_string()) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected the remove_suffix suffix string to be a string", arguments[0].position());
         return nullptr;
     }
 
-    auto suffix_str = suffix->resolve_as_list(this).release_value_but_fixme_should_propagate_errors()[0];
-    auto values = value->resolve_as_list(this).release_value_but_fixme_should_propagate_errors();
+    auto suffix_str = TRY(suffix->resolve_as_list(this))[0];
+    auto values = TRY(value->resolve_as_list(this));
 
     Vector<NonnullRefPtr<AST::Node>> nodes;
 
     for (auto& value_str : values) {
-        String removed = String::from_utf8(value_str).release_value_but_fixme_should_propagate_errors();
+        String removed = TRY(String::from_utf8(value_str));
 
         if (value_str.bytes_as_string_view().ends_with(suffix_str))
-            removed = removed.substring_from_byte_offset(0, value_str.bytes_as_string_view().length() - suffix_str.bytes_as_string_view().length()).release_value_but_fixme_should_propagate_errors();
+            removed = TRY(removed.substring_from_byte_offset(0, value_str.bytes_as_string_view().length() - suffix_str.bytes_as_string_view().length()));
 
         nodes.append(AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), move(removed), AST::StringLiteral::EnclosureType::None));
     }
@@ -266,7 +266,7 @@ RefPtr<AST::Node> Shell::immediate_remove_suffix(AST::ImmediateExpression& invok
     return AST::make_ref_counted<AST::ListConcatenate>(invoking_node.position(), move(nodes));
 }
 
-RefPtr<AST::Node> Shell::immediate_remove_prefix(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_remove_prefix(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to remove_prefix", invoking_node.position());
@@ -274,30 +274,30 @@ RefPtr<AST::Node> Shell::immediate_remove_prefix(AST::ImmediateExpression& invok
     }
 
     auto prefix = const_cast<AST::Node&>(arguments[0]).run(this);
-    auto value = const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this));
 
     if (!prefix->is_string()) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected the remove_prefix prefix string to be a string", arguments[0].position());
         return nullptr;
     }
 
-    auto prefix_str = prefix->resolve_as_list(this).release_value_but_fixme_should_propagate_errors()[0];
-    auto values = value->resolve_as_list(this).release_value_but_fixme_should_propagate_errors();
+    auto prefix_str = TRY(prefix->resolve_as_list(this))[0];
+    auto values = TRY(value->resolve_as_list(this));
 
     Vector<NonnullRefPtr<AST::Node>> nodes;
 
     for (auto& value_str : values) {
-        String removed = String::from_utf8(value_str).release_value_but_fixme_should_propagate_errors();
+        String removed = TRY(String::from_utf8(value_str));
 
         if (value_str.bytes_as_string_view().starts_with(prefix_str))
-            removed = removed.substring_from_byte_offset(prefix_str.bytes_as_string_view().length()).release_value_but_fixme_should_propagate_errors();
+            removed = TRY(removed.substring_from_byte_offset(prefix_str.bytes_as_string_view().length()));
         nodes.append(AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), move(removed), AST::StringLiteral::EnclosureType::None));
     }
 
     return AST::make_ref_counted<AST::ListConcatenate>(invoking_node.position(), move(nodes));
 }
 
-RefPtr<AST::Node> Shell::immediate_split(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_split(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to split", invoking_node.position());
@@ -305,14 +305,14 @@ RefPtr<AST::Node> Shell::immediate_split(AST::ImmediateExpression& invoking_node
     }
 
     auto delimiter = const_cast<AST::Node&>(arguments[0]).run(this);
-    auto value = const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this));
 
     if (!delimiter->is_string()) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected the split delimiter string to be a string", arguments[0].position());
         return nullptr;
     }
 
-    auto delimiter_str = delimiter->resolve_as_list(this).release_value_but_fixme_should_propagate_errors()[0];
+    auto delimiter_str = TRY(delimiter->resolve_as_list(this))[0];
 
     auto transform = [&](auto const& values) {
         // Translate to a list of applications of `split <delimiter>`
@@ -338,7 +338,7 @@ RefPtr<AST::Node> Shell::immediate_split(AST::ImmediateExpression& invoking_node
     }
 
     // Otherwise, just resolve to a list and transform that.
-    auto list = value->resolve_as_list(this).release_value_but_fixme_should_propagate_errors();
+    auto list = TRY(value->resolve_as_list(this));
     if (!value->is_list()) {
         if (list.is_empty())
             return AST::make_ref_counted<AST::ListConcatenate>(invoking_node.position(), NonnullRefPtrVector<AST::Node> {});
@@ -349,14 +349,14 @@ RefPtr<AST::Node> Shell::immediate_split(AST::ImmediateExpression& invoking_node
             StringBuilder builder;
             for (auto code_point : Utf8View { value }) {
                 builder.append_code_point(code_point);
-                split_strings.append(builder.to_string().release_value_but_fixme_should_propagate_errors());
+                split_strings.append(TRY(builder.to_string()));
                 builder.clear();
             }
         } else {
             auto split = StringView { value }.split_view(delimiter_str, options.inline_exec_keep_empty_segments ? SplitBehavior::KeepEmpty : SplitBehavior::Nothing);
             split_strings.ensure_capacity(split.size());
             for (auto& entry : split)
-                split_strings.append(String::from_utf8(entry).release_value_but_fixme_should_propagate_errors());
+                split_strings.append(TRY(String::from_utf8(entry)));
         }
         return AST::make_ref_counted<AST::SyntheticNode>(invoking_node.position(), AST::make_ref_counted<AST::ListValue>(move(split_strings)));
     }
@@ -364,7 +364,7 @@ RefPtr<AST::Node> Shell::immediate_split(AST::ImmediateExpression& invoking_node
     return transform(AST::make_ref_counted<AST::ListValue>(list)->values());
 }
 
-RefPtr<AST::Node> Shell::immediate_concat_lists(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_concat_lists(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     NonnullRefPtrVector<AST::Node> result;
 
@@ -372,12 +372,12 @@ RefPtr<AST::Node> Shell::immediate_concat_lists(AST::ImmediateExpression& invoki
         if (auto* list = dynamic_cast<const AST::ListConcatenate*>(&argument)) {
             result.extend(list->list());
         } else {
-            auto list_of_values = const_cast<AST::Node&>(argument).run(this)->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors();
+            auto list_of_values = TRY(const_cast<AST::Node&>(argument).run(this)->resolve_without_cast(this));
             if (auto* list = dynamic_cast<AST::ListValue*>(list_of_values.ptr())) {
                 for (auto& entry : static_cast<Vector<NonnullRefPtr<AST::Value>>&>(list->values()))
                     result.append(AST::make_ref_counted<AST::SyntheticNode>(argument.position(), entry));
             } else {
-                auto values = list_of_values->resolve_as_list(this).release_value_but_fixme_should_propagate_errors();
+                auto values = TRY(list_of_values->resolve_as_list(this));
                 for (auto& entry : values)
                     result.append(AST::make_ref_counted<AST::StringLiteral>(argument.position(), entry, AST::StringLiteral::EnclosureType::None));
             }
@@ -387,7 +387,7 @@ RefPtr<AST::Node> Shell::immediate_concat_lists(AST::ImmediateExpression& invoki
     return AST::make_ref_counted<AST::ListConcatenate>(invoking_node.position(), move(result));
 }
 
-RefPtr<AST::Node> Shell::immediate_filter_glob(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_filter_glob(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     // filter_glob string list
     if (arguments.size() != 2) {
@@ -395,7 +395,7 @@ RefPtr<AST::Node> Shell::immediate_filter_glob(AST::ImmediateExpression& invokin
         return nullptr;
     }
 
-    auto glob_list = const_cast<AST::Node&>(arguments[0]).run(*this)->resolve_as_list(*this).release_value_but_fixme_should_propagate_errors();
+    auto glob_list = TRY(const_cast<AST::Node&>(arguments[0]).run(*this)->resolve_as_list(*this));
     if (glob_list.size() != 1) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected the <glob> argument to filter_glob to be a single string", arguments[0].position());
         return nullptr;
@@ -431,7 +431,7 @@ RefPtr<AST::Node> Shell::immediate_filter_glob(AST::ImmediateExpression& invokin
     return AST::make_ref_counted<AST::ListConcatenate>(invoking_node.position(), move(result));
 }
 
-RefPtr<AST::Node> Shell::immediate_join(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_join(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to join", invoking_node.position());
@@ -444,166 +444,166 @@ RefPtr<AST::Node> Shell::immediate_join(AST::ImmediateExpression& invoking_node,
         return nullptr;
     }
 
-    auto value = const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments[1]).run(this)->resolve_without_cast(this));
     if (!value->is_list()) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected the joined list to be a list", arguments[1].position());
         return nullptr;
     }
 
-    auto delimiter_str = delimiter->resolve_as_list(this).release_value_but_fixme_should_propagate_errors()[0];
+    auto delimiter_str = TRY(delimiter->resolve_as_list(this))[0];
     StringBuilder builder;
-    builder.join(delimiter_str, value->resolve_as_list(*this).release_value_but_fixme_should_propagate_errors());
+    builder.join(delimiter_str, TRY(value->resolve_as_list(*this)));
 
-    return AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), builder.to_string().release_value_but_fixme_should_propagate_errors(), AST::StringLiteral::EnclosureType::None);
+    return AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), TRY(builder.to_string()), AST::StringLiteral::EnclosureType::None);
 }
 
-RefPtr<AST::Node> Shell::immediate_value_or_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_value_or_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to value_or_default", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     if (!local_variable_or(name, ""sv).is_empty())
         return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
     return arguments.last();
 }
 
-RefPtr<AST::Node> Shell::immediate_assign_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_assign_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to assign_default", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     if (!local_variable_or(name, ""sv).is_empty())
         return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
-    auto value = const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_without_cast(*this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_without_cast(*this));
     set_local_variable(name.to_deprecated_string(), value);
 
     return make_ref_counted<AST::SyntheticNode>(invoking_node.position(), value);
 }
 
-RefPtr<AST::Node> Shell::immediate_error_if_empty(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_error_if_empty(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to error_if_empty", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     if (!local_variable_or(name, ""sv).is_empty())
         return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
-    auto error_value = const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto error_value = TRY(const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_as_string(*this));
     if (error_value.is_empty())
-        error_value = String::formatted("Expected {} to be non-empty", name).release_value_but_fixme_should_propagate_errors();
+        error_value = TRY(String::formatted("Expected {} to be non-empty", name));
 
     raise_error(ShellError::EvaluatedSyntaxError, error_value.bytes_as_string_view(), invoking_node.position());
     return nullptr;
 }
 
-RefPtr<AST::Node> Shell::immediate_null_or_alternative(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_null_or_alternative(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to null_or_alternative", invoking_node.position());
         return nullptr;
     }
 
-    auto value = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_without_cast(*this).release_value_but_fixme_should_propagate_errors();
-    if ((value->is_string() && value->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors().is_empty()) || (value->is_list() && value->resolve_as_list(*this).release_value_but_fixme_should_propagate_errors().is_empty()))
+    auto value = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_without_cast(*this));
+    if ((value->is_string() && TRY(value->resolve_as_string(*this)).is_empty()) || (value->is_list() && TRY(value->resolve_as_list(*this)).is_empty()))
         return make_ref_counted<AST::SyntheticNode>(invoking_node.position(), value);
 
     return arguments.last();
 }
 
-RefPtr<AST::Node> Shell::immediate_defined_value_or_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_defined_value_or_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to defined_value_or_default", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     if (!find_frame_containing_local_variable(name))
         return arguments.last();
 
     return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 }
 
-RefPtr<AST::Node> Shell::immediate_assign_defined_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_assign_defined_default(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to assign_defined_default", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     if (find_frame_containing_local_variable(name))
         return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
-    auto value = const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_without_cast(*this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_without_cast(*this));
     set_local_variable(name.to_deprecated_string(), value);
 
     return make_ref_counted<AST::SyntheticNode>(invoking_node.position(), value);
 }
 
-RefPtr<AST::Node> Shell::immediate_error_if_unset(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_error_if_unset(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to error_if_unset", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     if (find_frame_containing_local_variable(name))
         return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
-    auto error_value = const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto error_value = TRY(const_cast<AST::Node&>(arguments.last()).run(*this)->resolve_as_string(*this));
     if (error_value.is_empty())
-        error_value = String::formatted("Expected {} to be set", name).release_value_but_fixme_should_propagate_errors();
+        error_value = TRY(String::formatted("Expected {} to be set", name));
 
     raise_error(ShellError::EvaluatedSyntaxError, error_value.bytes_as_string_view(), invoking_node.position());
     return nullptr;
 }
 
-RefPtr<AST::Node> Shell::immediate_null_if_unset_or_alternative(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_null_if_unset_or_alternative(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 2) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 2 arguments to null_if_unset_or_alternative", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     if (!find_frame_containing_local_variable(name))
         return arguments.last();
 
     return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 }
 
-RefPtr<AST::Node> Shell::immediate_reexpand(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_reexpand(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 1) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 1 argument to reexpand", invoking_node.position());
         return nullptr;
     }
 
-    auto value = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto value = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     return parse(value, m_is_interactive, false);
 }
 
-RefPtr<AST::Node> Shell::immediate_length_of_variable(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_of_variable(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
     if (arguments.size() != 1) {
         raise_error(ShellError::EvaluatedSyntaxError, "Expected exactly 1 argument to length_of_variable", invoking_node.position());
         return nullptr;
     }
 
-    auto name = const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this).release_value_but_fixme_should_propagate_errors();
+    auto name = TRY(const_cast<AST::Node&>(arguments.first()).run(*this)->resolve_as_string(*this));
     auto variable = make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
     return immediate_length_impl(
@@ -612,7 +612,7 @@ RefPtr<AST::Node> Shell::immediate_length_of_variable(AST::ImmediateExpression&
         false);
 }
 
-RefPtr<AST::Node> Shell::run_immediate_function(StringView str, AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
+ErrorOr<RefPtr<AST::Node>> Shell::run_immediate_function(StringView str, AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const& arguments)
 {
 #define __ENUMERATE_SHELL_IMMEDIATE_FUNCTION(name) \
     if (str == #name)                              \
diff --git a/Userland/Shell/Shell.h b/Userland/Shell/Shell.h
index 9d3ee04522..dd6a22502c 100644
--- a/Userland/Shell/Shell.h
+++ b/Userland/Shell/Shell.h
@@ -156,7 +156,7 @@ public:
     bool run_file(DeprecatedString const&, bool explicitly_invoked = true);
     ErrorOr<bool> run_builtin(const AST::Command&, NonnullRefPtrVector<AST::Rewiring> const&, int& retval);
     bool has_builtin(StringView) const;
-    RefPtr<AST::Node> run_immediate_function(StringView name, AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const&);
+    ErrorOr<RefPtr<AST::Node>> run_immediate_function(StringView name, AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const&);
     static bool has_immediate_function(StringView);
     void block_on_job(RefPtr<Job>);
     void block_on_pipeline(RefPtr<AST::Pipeline>);
@@ -423,13 +423,13 @@ private:
     virtual void custom_event(Core::CustomEvent&) override;
 
 #define __ENUMERATE_SHELL_IMMEDIATE_FUNCTION(name) \
-    RefPtr<AST::Node> immediate_##name(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const&);
+    ErrorOr<RefPtr<AST::Node>> immediate_##name(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const&);
 
     ENUMERATE_SHELL_IMMEDIATE_FUNCTIONS();
 
 #undef __ENUMERATE_SHELL_IMMEDIATE_FUNCTION
 
-    RefPtr<AST::Node> immediate_length_impl(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const&, bool across);
+    ErrorOr<RefPtr<AST::Node>> immediate_length_impl(AST::ImmediateExpression& invoking_node, NonnullRefPtrVector<AST::Node> const&, bool across);
 
 #define __ENUMERATE_SHELL_BUILTIN(builtin) \
     ErrorOr<int> builtin_##builtin(Main::Arguments);